Stable high solids water-in-oil emulsions of water soluble polymers

ABSTRACT

A WATER-IN-OIL EMULSION WHICH HAS A WATER-SOLUBLE VINYL ADDITION POLYMER CONCENTRATION BETWEEN 20 AND 50% BY WEIGHT BASED ON EMULSION WHICH EXHIBITS UNUSUAL STABILITY PROPERTIES.

United States Patent 3,826,771 STABLE lHllGH SOLIDS WATER-llN-OIL EMULSTONS OF WATER SOLUBLE POLYMERS Donald R. Anderson, Oswego, and Alvin 1i. lFrisque, La Grange, 111., assignors to Nalco Chemical Company, Chicago, ill.

N0 Drawing. Continuation-impart of application Ser. No. 320,012, Jan. 11, 1973, which is a continuation-in-part of application Ser. No. 161,967, July 12, 1971, now abandoned. This application Nov. 6, 1973, Ser. No.

Int. Cl. C08f 1/13 U.S. Cl. 26029.6 H 14 Claims ABSTRACT OF THE DISCLOSURE A water-in-oil emulsion which has a water-soluble vinyl addition polymer concentration between 20 and 50% by weight based on emulsion which exhibits unusual stability properties.

This is a continuationin-part application of application Ser. No. 320,012 filed Jan. 11, 1973, which is a continuation-in-part of application Ser. No. 161,967 filed July 12, 1971 both now abandoned.

INTRODUCTION This invention concerns a water-in'oil polymer and copolymer emulsion having a polymer concentration between 20 and 50% by weight based on emulsion exhibiting unusual stability properties.

Various synthetic and naturally-occurring water-soluble polymers have been developed which exhibit, in aqueous solution, superior thickening and floculating properties. These polymers are being used increasingly in a number of commercial applications such as, for example, in the clarification of aqueous systems, in paper-making operations, in the treatment of sewage and industrial waste, as stabilizers for drilling muds, and in the secondary recovery of petroleum water flooding.

Although these polymers are most often available commercially as powders or as finely-divided solids, they are most frequently utilized as aqueous solutions. This necessitates that the solid polymer material be dissolved in water. This is a time consuming step as well as one which has serious drawbacks with respect to the actual dispersion of solids into the aqueous media.

The products made under the process described and "ice TABLE I Monomer Phase Concentrations in U.S. 3,248,393

Example: Monomer Phase Percent It should be noted that the high monomer phase concentration is 33.91%, with the majority of the examples being within the range 22.5 to 29.0%. In addition, the products manufactured via the Vanderhotf technique are unstable and drop out of the emulsion within a short period of time. It is clear that these extremely low values for the monomer and water do not achieve the minimum monomer phase alleged by Vanderhofif. Thus, it can be readily seen that this art is practiced for the most part below the claimed ranges.

U.S. 3.041,3l8, Hess, teaches a process for recovering water-soluble polymers. Disclosed therein is a method for preparing emulsions containing polymers. This method involves the addition of an oil-emulsifier phase to an aqueous solution of a water-soluble polymer. Such emulsions containing 20 to by Weight of vinyl addition polymers having molecular weights in excess of 1,000,000 cannot be prepared via the technique used in Hess for the reason that it is not possible to prepare aqueous solutions containing high enough concentrations of the polymer.

For example, to prepare 100 grams of an emulsion containing approximately /3 Water, hydrophobic liquid and /a polymer, it would be necessary to dissolve 33 /3 grams of the high molecular weight polymer in 33 /3 grams of water. It simply is not possible to prepare this 50% aqueous solution of polymer. To exemplify the above discussion, several polymers are shown below in Table II with their solution characteristics noted.

TABLE II Aqueous Molecular solution weight concen- (approxtration, Test No. Polymer composition imate) percent Remarks 1 50% Na aerylate, 50% acrylamide. 11, 000,000 10.0 Intrinsic viscosity=21.3; rubberlike features. 2... 25% DMAl-IM, 75% acrylamid 5,700,000 10.0 Intrinsic viscosity=l0.5; rubberlike.

Na polystyrene sult'onate 6, 806,000 3.8 Rubhery or gel like. 4 Na polyaerylate 8,000, 000 3. 1 Do.

1 DMAEM:dimethylaminoethyl methacrylate. claimed in U.S. Pat. 3,284,393, Vanderhoii, illustrate a water-in-oil emulsion polymerization method for the production of dry solid polymers. The Vanderhoif method broadly describes a monomer phase range between 30 and by weight of the emulsion. Monomer phase is defined therein as monomer plus water. However, in his illustrative examples, only two of the examples had a mon- 7 omer phase greater than 30%. Shown below in Table I are the monomer phase concentrations in U.S. 3,248,393.

the emulsion of a water-soluble vinyl addition polymer having a molecular weight of at least 1,000,000 and from 45 to 55% by weight of the emulsion of water. In addition, the present invention claims an inert hydrophobic liquid in a concentration of to 25% by weight of the emulsion.

The aqueous phase of the present invention is the same as the monomer phase as described in Vanderhotf, that is, it is the sum of the vinyl addition polymer and water in the composition. In the present invention a typical vinyl addition polymer concentration is 30%. A typical water concentration is 45% by weight of the emulsion. Thus, the total aqueous phase is outside that illustrated in Vanderhoif, as well as being substantially greater than the range practiced in Vanderhoff.

The present invention exhibits a stable emulsion composition. The stability is one of the key factors of this invention. The stability exhibited by the composition is defined as the ability to maintain the dispersion of the polymer particles throughout the emulsion for a period of at least three weeks at which time the dispersion can be reformed with only slight agitation. The stability exhibited by the composition of the present invention is completely unexpected. The product made under Vanderhotf, US. Patent 3,284,393 does not exhibit the stability properties of this invention. Upon standing for a similar three-week period the product disintegrates and is non-redispersible with vigorous agitation. Thus, the increased water-to-oil ratio in the present invention gives the increased stability to the emulsion product.

OBJECT S An object of this invention is to provide an emulsion composition.

Another object of this invention is to provide an emulsion composition which has a high degree of stability.

Another object of this invention is to provide an emulsion composition which has a polymer content between 20 and 50% by weight based on emulsion.

Another object of this invention is to provide an emulsion composition which has an aqueous phase of at least 75% based on the emulsion.

THE INVENTION This invention is directed to a stable water-in-oil polymer emulsion which contains dispersed therein finelydivided particles of water-soluble vinyl addition polymer in the concentration of at least 20% based on emulsion. This can be termed a polymer-containing emulsion.

From a commercial standpoint it is beneficial that the polymer emulsions thus described be stable, yet at the same time contain relatively large amounts of polymer. One method of assuring that the polymers do not precipitate when dispersed in the emulsion is that the particle size of the polymer be as small as possible. Thus, polymers dispersed in the emulsion are quite stable when the particle size is within the range of 2 millimicrons up to about 5 microns. The preferred particle size is within the range of 5 millimicrons and 3 microns.

The stable water-in-oil emulsion comprises:

(1) an aqueous phase; (2) an inert hydrophobic liquid; and (3) a water-in-oil emulsifying agent.

The primary feature of this polymer-containing emulsion is that it remains stable with passage of time. The stability, which this composition exhibits as defined above is the maintenance of the dispersion of the polymer particles throughout the emulsion for a period of at least three weeks at which time the dispersion can be reformed with only slight agitation.

The polymer-containing emulsion of this invention is comprised in an aqueous phase ranging between 75 and 95% by weight of the emulsion. The aqueous phase is defined as a sum of polymer or copolymer and the water present in the composition. The preferred range is between 75 and by weight of the emulsion. The most preferred range is between 75 and 80% by weight of the emulsion.

The present invention has a polymer concentration between 20 and 50% by weight of the emulsion. A preferred range is between 25 and 40% by weight of the emulsion. The most preferred range is between 30 and 35% by weight of the emulsion.

The polymers most commonly used in many industrial applications are acrylamide polymers which include polyacrylamide and its water soluble copolymeric derivatives such as, for instance, acrylic acid, methacrylic acid and acrylonitrile. The copolymers contain from about 5 to by weight of acrylamide.

Other water-soluble vinyl polymers are described in detail in the following US. Pats: 3,418,237; 3,259,570 and 3,171,805 which are incorporated herein by reference. In examining the disclosures of these patents it will be seen that the water-soluble polymers may be either cationic or anionic and, in some instances, the ionic charges are sufficiently slight so that the polymers may be considered nonionic. For example, water-soluble polymers and co polymers of allyl, diallyl amines or dimethylaminoethylmethacrylate are cationic. Polymers such as polyacrylamide are nonionic and polymers such as polyacrylic acid or polystyrene sulfonates are anionic.

The molecular weight of the polymers described above may vary over a wide range, e.g. 10,000 to 25,000,000. The preferred polymer has a molecular weight in excess of 1,000,000.

The organic or oil phase is comprised of an inert hydrophobic liquid. The hydrophobic liquid comprises between 5 and 25% by weight of the emulsion. The preferred range is between 10 and 25 by weight of the emulsion. The most preferred range is between 20 and 25% by weight of the emulsion.

The oils used in preparing these emulsions may be selected from a large group of organic liquids which include liquid hydrocarbons and substituted liquid hydrocarbons. Preferred group of organic liquids are hydrocarbon liquids, most preferably aliphatic hydrocarbon liquids, which include blends of aromatic and aliphatic hydrocarbon compounds which contain from 4 to 8 carbon atoms. Thus, such organic hydrocarbon liquids as benzene, xylene, toluene, mineral oils, kerosenes, naphthas, and in certain instances, petroleums may be used. A particularly useful oil from the standpoint of its physical and chemical properties is the branch-chain isoparaffinic solvent sold by Humble Oil and Refinery Company under the tradename ISOPAR M. Typical specifications of this narrow-cut isoparaffinic solvent are set forth below in Table III.

TABLE III Min- Max- Specrficatron properties imum imum Test method Gravity, API at (BO/60 F 48. 0 51. 0 ASTM D 287 Color, Sayholt. 30 ASTM D 156 istnllfhne point, F 185 ASTM D 611 u ur p.p.m 10 1 Distillation, F; ASTM D 1266 1B1 400 410 ASTM D 86 Dry point 495 ASTM D 86 Flash point, F? ASTM D 93 1 Nephelometric mod. 1 Peusky-Martens closed cup.

the emulsion and is disposed between the two basic phases. The preferred range is between 1.0 and 15% by Weight of the emulsion. The most preferred range is be tween 2 and by weight of the emulsion.

The stable water-in-oil emulsion of the present invention exhibits the unique ability of rapidly dissolving into aqueous solution. The polymencontaining emulsion releases the polymer in water in the presence of a surfactant in a very short-period of time when compared to the amount of time required to dissolve a solid form of the polymer. This inversion technique is described in US. Patent 3,624,019, Anderson et al.

The water-in-oil polymer containing emulsions of this invention are prepared by the techniques used in US. 3,284,393, Vanderhotf, which is incorporated herein by reference. Basically, the emulsions are prepared by:

A. Using as a reaction mixture:

(1) water which contains dissolved therein a watersoluble vinyl addition monomer thereby producing a monomer phase, having a concentration of from 75 to 95 by weight of the emulsion;

(2) an inert hydrophobic liquid ranging between 5 and 25% by weight of the emulsion;

(3) water-in-oil emulsifying agent in a concentration of 0.1 to and (4) a free radical initiator whereby a water-in-oil emulsion is formed; and

B. Heating the emulsion under free radical conditions to polymerize the water-soluble vinyl addition monomer containing emulsion thereby producing a stable water-inoil emulsion which contains dispersed therein finely-divided particles of a water-soluble vinyl addition polymer.

The following examples show ways in which the invention has been practiced:

EXAMPLE 1 Acrylamide-methacrylic acid emulsion recipe Grams ISOPAR M 27.6 Sorbitan Monostearate 1.65

Water 40.20 Acrylamide 34.51 Methacrylic Acid 2.31 Sodium Hydroxide 2.29 2,2-azobis(isobutyronitrile) 0.07

The sorbitan monostearate was dissolved in the ISOPAR M and the resulting solution was poured into a two liter glass reactor fitted with a stirrer, thermometer, and nitrogen purge. The monomer solution was prepared by dissolving the acrylamide and methacrylic acid in water. The pH of the monomer solution was adjusted to 8.5 with sodium hydroxide. The monomer solution was added to the organic phase with rapid agitation. The reactor was purged for 30 minutes after which time the 2,2'-azobis(isobutyronitrile) dissolved in acetone was added to the mixture. The emulsion was heated to 60 C. with agitation. The reaction proceeded for 2 /2 hours at which time it has reached completion. The resulting product was a stable emulsion which was inverted in water by the use of a surfactant. The resulting polymer solution gave a viscosity of 150 c.p.s. on a 1% solution.

EXAMPLE 2 Acrylamide'acrylic acid emulsion recipe Grams ISOPAR M 28.10 Sorbitan Monostearate 1.85 Water 40.00 Acrylamide 33.90 Acrylic Acid 2.40 Sodium Hydroxide 2.30 2,2'-azobis(isobutyronitrile) 0.07

As in Example 1, the sorbitan monostearate was dissolved in the ISOPAR M and the resulting solution was poured into a two liter glass reactor fitted with a stirrer, thermometer, and nitrogen purge. The monomer solution was prepared by dissolving the acrylamide and acrylic acid in water. The pH of the monomer solution was adjusted to 8.5 with sodium hydroxide. The monomer solu tion was added to the organic phase with rapid agitation. The reactor was purged for 30 minutes after which time the 2,2-azobis(isobutyronitrile) dissolved in acetone was added to the mixture. The emulsion was heated to 60 C. with agitation. The reaction proceeded for 2 /2 hours at which time it had reached completion. The resulting product was a stable emulsion which was inverted in water by use of a surfactant. The resulting polymer solution gave a viscosity of 225 cps. on a 1% solution.

EXAMPLE 3 Dimethylaminoethyl methacrylate emulsion recipe Grams ISOPAR M 27.60 Sorbitan Monostearate 1.65 Water 40.20

Dimethylaminoethyl methacrylate (DMAEM) 38.82

Sodium Hydroxide 2.29 2,2'-azobis(isobutyronitrile) 0.07

The sorbitan monostearate was dissolved in the ISOPAR M and the resulting solution was poured into a two liter glass reactor fitted with a stirrer, thermometer, and nitrogen purge. The monomer solution was prepared by dissolving the DMAEM in water. The pH in monomer solution was adjusted to 8.3 with sodium hydroxide. The monomer solution was added to the organic phase with rapid agitation. The reactor was purged for 30 minutes after which time the 2,2'-azobis(isobutyronitrile) dissolved in acetone was added to the mixture. The emulsion was heated to 60 C. with agitation. The reaction proceeded for 5 hours at which time it had reached completion. The resulting product was a stable emulsion which was inverted in water by the use of a surfactant.

EXAMPLE 4 Polystyrene sulfonate emulsion recipe Grams ISOPAR M 27.60 Sorbitan Monostearate 1.65 Water 40.20 Styrene Sulfonate 36.80 Sodium Hydroxide 2.29 2,2azobis(isobutyronitrile) 0.07

This reaction was performed using the identical procedure as in the previous examples. The reaction proceeded for 8 hours at which time it had reached completion. The resulting product yielded a stable emulsion which was inverted in water by use of a surfactant.

We claim:

1. A stable Water-in-oil emulsion containing a dispersion therein of finely-divided particles of water-soluble vinyl addition polymer, having a molecular Weight of at least 1,000,000, said emulsion being characterized as having the ability to maintain a dispersion throughout said emulsion for a period of at least three weeks at which time said dispersion can be reformed with slight agitation, said emulsion comprising:

A. an aqueous phase ranging between 75 and by weight of the emulsion which is comprised of:

( 1) a water-soluble vinyl addition polymer having a concentration between 20 and 50% by Weight of the emulsion, said polymer having a particle size within the range of 2 millimicrons to 5 microns,

(2) water ranging between 45 and 55% by weight of the emulsion;

B. a liquid hydrocarbon ranging between and 25% by weight of the emulsion; and additionally C. a water-in-oil emulsifying agent disposed between said aqueous phase and said liquid hydrocarbon and having a concentration between 0.1 and by weight of the emulsion, wherein:

(1) said Water-in-oil emulsion is prepared by using as a reaction mixture:

(a) water which contains dissolved therein a water-soluble vinyl addition monomer thereby producing a monomer phase having a concentration of from 75 to 95% by weight of the emulsion;

(b) a liquid hydrocarbon ranging between 5 and by weight of the emulsion;

(c) 'Water-in-oil emulsifying agent in a concentration of 0.1 to 15% and (d) a free radical initiator whereby a waterin-oil emulsion is formed; and

(2) heating said emulsion under free radical conditions to polymerize the water-soluble vinyl addition monomer containing emulsion thereby producing a stable water-in-oil emulsion which contains dispersed therein finely divided particles of a water-soluble vinyl addition polymer.

2. The stable water-in-oil emulsion of Claim 1 wherein the water-soluble vinyl addition polymer has a concentra tion between 25 and 40% by Weight of the emulsion.

3. The stable Water-in-oil emulsion of Claim 1 wherein the water-soluble vinyl addition polymer is from the group consisting of acrylamide polymers and water-soluble salts of polyacrylic acid.

4. The stable water-in-oil emulsion of Claim 1 wherein said water-soluble vinyl addition polymer is a Water-soluble salt of polyacrylic acid.

5. The stable water-in-oil emulsion of Claim 3 wherein said water-soluble vinyl addition polymer is a copolymer of acrylamide and acrylic acid.

6. The stable water-in-oil emulsion of Claim 3 wherein said Water-soluble vinyl addition polymer is a copolymer of acrylamide and methacrylic acid.

7. The stable water-in-oil emulsion of Claim 1 wherein the liquid hydrocarbon is a liquid aliphatic hydrocarbon.

8. The method of Claim 3 wherein the liquid hydrocarbon is a liquid aliphatic hydrocarbon.

9. A stable water-in-oil emulsion containing a dispersion therein of finely divided particles of water-soluble vinyl addition polymer, having a molecular weight of at least 1,000,000, said emulsion being chaacterized as hav ing the ability to maintain a dispersion throughout said emulsion for a period of at least three weeks at which time said dispersion can be reformed with slight agitation, said emulsion comprising:

A. an aqueous phase ranging between 75 and 95% by weight of the emulsion which is comprised of:

(1) a water-soluble vinyl addition polymer having a concentration between 20 and 50% by weight of the emulsion, said polymer having a particle size within the range of 2 millimicrons to 5 microns,

(2) water ranging between and by Weight of the emulsion;

B. a liquid aliphatic hydrocarbon ranging between 5 and 25% by Weight of the emulsion; and additionally C. a water-in-oil emulsifying agent disposed between said aqueous phase and said liquid hydrocarbon and having a concentration between 0.1 and 15% by weight of the emulsion, wherein:

( 1) said water-in-oil emulsion is prepared by using as a reaction mixture:

(a) water which contains dissolved therein a water-soluble vinyl addition monomer thereby producing a monomer phase, having a concentration of from to by weight of the emulsion;

(b) a liquid aliphatic hydrocarbon ranging between 5 and 25% by weight of the emulsion;

(0) water-in-oil emulsifying agent in a concentration of 0.1 to 15%; and

(d) a free radical initiator whereby a Waterin-oil emulsion is formed; and

(2) heating said emulsion under free radical conditions to polymerize the water-soluble vinyl addition monomer containing emulsion thereby producing a stable Water-in-oil emulsion which contains dispersed therein finely divided parti cles of a water-soluble vinyl addition polymer.

10. The stable water-in-oil emulsion of Claim 9 wherein the water-soluble vinyl addition polymer has a concentration between 25 and 40% by weight of the emulsion.

11. The stable water-in-oil emulsion of Claim 9 wherein the water-soluble vinyl addition polymer is from the group consisting of acrylamide polymers and water-soluble salts of polyacrylic acid.

12. The stable water-in-oil emulsion of Claim 9 wherein said water-soluble vinyl addition polymer is a watersoluble salt of polyacrylic acid.

13. The stable water-in-oil emulsion of Claim 9 wherein said water-soluble vinyl addition polymer is a copolymer of acrylamide and acrylic acid.

14. The stable wat-er-in-oil emulsion of Claim 9 wherein said water-soluble vinyl addition polymer is a copolymer of acrylamide and methacrylic acid.

References Cited UNITED STATES PATENTS 3,041,318 6/1962 Hess. 3,284,393 11/1966 Vanderhoff et al. 3,624,019 11/1971 Anderson et al.

FOREIGN PATENTS 51,095 7/1968 Romania. 1,516,426 1/1968 France.

MELVIN GOLDSTEIN, Primary Examiner U.S. Cl. X.R. 26029.6 WQ 

